Mechanical separation of speakers is not for everybody but it works for me too....
Interaural Crosstalk And Loudspeaker Setup
When listening to two channel stereo audio reproduction sounds from the right channel loudspeaker are heard by both the listener's right ear and left ear. Sounds from the left channel loudspeaker are similarly heard by both the listener's left and right ear. This fact has been labelled interaural crosstalk. Here's a brief discussion of it from the Steve Hoffman forum.
Interaural crosstalk can be enhanced or diminished via electronic means and even by the physical design of the loudspeaker. Can it also be accomplished via loudspeaker placement and acoustic treatments? Toe-in could be a tool, but I'm thinking of a setup I saw back towards the end of the last century. I remember visiting a retailer who had a large acoustic panel, maybe 6 ft by 6 ft, that was supposed to be placed between the loudspeaker, but perpendicular to the plane of the loudspeakers. The idea was that the panel would lessen the crosstalk at the listener position. I never heard a demo of the product so I have no idea if or how well it worked.
Does anybody have experience with setting up their listening space in this manner? If so, what did you think? BTW, I've look at near countless virtual system pics and I've never seen this layout. That should tell me something, but maybe not.
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The one single thing that bothers me most about interaural crosstalk is the cancellation dip that occurs at the ears for the phantom center. For a typical 60 degree triangle this first dip occurs around 2 kHz, which is about as bad a place for a dip that you could ask for, taking the crispness and articulation out of center panned vocals and instruments. If you push the speakers closer together you can push the first cancelation frequency up higher. That's good, but then the stereo effect is also minimized. If you push the speakers wider apart, that will push the first cancel down below 1 kHz, which I found is also good, as the upper frequencies will not get comb filtered as severely because of improved head shadowing. Lately I've been listening with about a 110 degree triangle and find this very satisfying in terms of giving a crisp, clear sounding center image. I get the impression that for me, late reflections can fill in below 1 kHz with less perceptible loss in clarity and presence than up at 2 kHz. I've also tried various crosstalk reduction methods, including a 3 speaker array that I dreamed up. They work, but seem to always come with a side effect or two. I haven't tried BACCH, but I tried a competitor product that sounded excellent. It didn't overly widen the soundstage while also producing an excellent tone and clarity for the phantom center. My main issue with it was latency from the processing. The other was that it needed the speakers to be closer together, and my room layout works better when the speakers are spaced wide apart, which to my ears sounds about as good overall. The best I've heard is from using a physical barrier. It's exceptionally clean and pure sounding, creating . I also think the arrangement ends up improving room acoustics considerably because it ends up dividing the whole room's early reflections into more exclusively left speaker reflections on the left side of the room, and right speaker reflections on the right side of the room. |
I have never seen or heard of the setup you describe with a baffle between the speakers but I have experimented with several electronic gizmos that are designed to address this issue. My favorite is a discontinued product called a BSG QOL processor. This unit goes between the preamp and the amp and it adds a significant illusion of depth to the soundstage. One of the nicest things about it is that you don't have to have your head in a vice to get the effect. I use it all the time - it makes virtually everything sound better. I bought a second one in case it fails. It got good reviews in Stereophile and TAS. They come up ocassionally on the used market and sell for a few hundred dollars (it retailed for $4K new). I also have a Carver C-9. It works well to add depth and detail to the soundstage but you have to set it up carefully and you have to have your head locked into position to get the effect. I also have a Black Ice FOZ SSX sound stage enhancer hooked up to my desktop system and it works very well. I tried it on my main rig and I didn't like it nearly as well as the BSG. Black Ice also makes a cross-talk reduction device that I haven't heard. The newest kid on the block is the BAACH Spatial Audio system. I haven't heard this yet but I'm looking forward to checking it out. From the reviews it sounds similar to the Carver unit in that you have to calibrate your head position exactly in the setup. That would be a deal killer for me but I would like to hear it anyway. |
Here the 3 main negative effects as described by Dr. Choueiri numerous articles : « Effects of Crosstalk
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The Polk SDA line of speakers mitigates interaural crosstalk. |
Every room sounds different depending on diffusion panels and absorption panels, corner traps, and reflection treatments, which can be either absorption or diffusion. Done right, it allows your system to be able to sound its best. If you buy these treatments, you could be looking at many thousands of $$$ of treatment, at least that is what it cost me; but well worth it |
In Nature we hear one sound source for the melody of a bird for example. In a living room with speakers we hear 2 sound sources for the same melody which impede the naturalness and information of spatial dimensions of the perceived sounds. 2 speakers stereo are unnatural situation .
In a word for our brain deciphering our 2 ears channels there is 4 speakers in the room:2 actual and 2 virtual because of the time interaural differential function. Choueiri explain it all and his mastery of the subject is complete. Read him. |
My room is under my acoustic mechanical control... My speakers heavily mechanically modified too... I also use a mechanical separation between the 2 speakers for my near listening situation...(unpractical for most people.)
If you want to know about crosstalk read articles by Edgar Choueiri the Specialist of this concept in audio ... |
why is this a concern ? try a headphones i suppose. Humans have evolved to hear from both ears at the same time thats how we localise things. you may just make it worce. we can tell distance, angle to sound, etc from the different time the audio araives at each ear. I think your just going to confuse your ear brain interface. |
My one observation is that the systems with the largest sweet spots and most stable image have very wide and even dispersion/power response. Perceived imaging is enhanced by diffusion between the speakers and even to the sides. It's not L/R crosstalk that I've heard mess up imaging so much as poorly managed in room reflections and gnarly off-axis response. Also, digital has nearly perfect L/R isolation vs. analog systems and yet they don’t really image much better IMHO. Some studies have suggested ~65 dB separation to be more than adequate. I guess my point is, while interaural crosstalk is a real thing it’s not really the problem we might think it is. The bigger issue is probably frequency cancellation in the center, making center channel speakers really useful for movies and 3 channel recordings as well as mono. |